Explosive rivet firing device



April 3, 1951 v. M. BUNTS EI'AL 2,547,437

EXPLOSIVE RIVET FIRING DEVICE Filed Aug. 22, 1947 l6 l0 2 14 1a III/Z iV.".."........"Jl I4- ]NVEN T DRE l I l -M VERNON M. BuNTs HENRYBHULBERT BY WW ATTURNEY Patented Apr. 3, 1951 EXPLOSIV E RIVET FIRINGDEVICE Vernon M. Bunts, East Syracuse, and Henry C. Holbert, Syracuse,.N. Y., assignors to Easy "Washing Machine Corporation, Syracuse; N.$Y.,

a corporation of Delaware Application August 22, 1947, Serial'No.770,062

'1 This invention relates .to heating. irons for the .settingandexploding of explosive rivets.

In the art of setting explosive rivets, it is neces- 'sary to conveyheat to the rivet head by contact therewith of a heated bar which, inorder to conduct heat satisfactorily, is usuallymade of .a good heatconductivematerial such as relatively pure copper. Such material isrelatively soft. and ductile, andis constantly subjected to. theelevated temperature required for quickly exploding the rivet through.contact with the head thereof. Wh'enIthe rivetis set .in sheet metalmembers having. some resiliency or yield, the reactive shockfrom therivethead against the detonating iron, isincreased, all resulting in theupsetting. of the copper tip. .In the. course of heating a number. ofrivets at a relatively fast rate, which requires relatively highironheat, the tip of the iron mushrooms, and in ashort space of time,becomes impractical of further use.

The present invention relates to a riveting iron construction which isso adapted as to prevent the mushrooming action of the iron tip, whileat the same time being capable of delivering heat to the rivet head withthe same dispatch as heretofore accomplished withplain, pure coppertips. The invention more particularly involves the use of a coppertip'h'aving the .end portion thereof positioned Within a steel or otherhardmetal sleeve or jacket capable of constraining while hot the coppertip from expanding or upsetting radially as a result of the axial shockreceived from the rivet upon detonation. The arrangement of such asleeve, while reducing somewhat the diameter of the copper heatconductor, by its nature acts as a slight heat insulator and permits thetip to operate at the same or a slightly higher temperature so that noloss in efficiency or time taken in exploding rivets is occasioned bythe construction.

The above and other novel features of the invention will appear morefully hereinafter from the following detailed description when taken inconjunction with the accompanying drawing. It is expressly understood,however, that the drawing is employed for purposes of illustration onlyand is not designed as a definition of the limits of the invention,reference being had for this purpose to the appended claims.

In the drawing, wherein similar reference characters refer to similarparts throughout the several views:

Figure 1 is a perspective view of an electric iron having a tipconstructed in accordance with the invention;

3. Claims. (Cl. 218-'19) Figure 2 isalongitudinal section of the tipconstruction;

Figure 3 is an. enlarged showing of a-tip in engagement with the head ofan explosiverivet; and

Figure 4 .isan exploded view in perspective showing the parts of whichthe tip is composed.

Referring .to Figures land 2, there is shown a typical hand electriciron or heating unit such as is ordinarily employed for solderingpurposes, the tip of which is constructed in accordance with theinvention to adapt it-fordetonating explosive rivets. Theriron isprovided with a central hollow core member In around which is located aheating coil [2, an insulating layer l4 and an outer protecting shell16. The core is providedwith anintegral collar l8, the hollow bore- 20being adapted to receive the shank end of a'tip assembly. The collar isalso; provided with a set screw"22"for affixing the shank of such tipassembly within the core.

In order to provide a' tip adapted to' contact the heads of 'rivets ofthe'explosive type which will withstand the repeated shock or detonationof the rivet contacted and the heat of the tip, the contactingend ofthe-tip is protected'with a sleeve ofrelativelyhard material such" asstee or the like.

In the form shown, the shank portion 24* of the tip assembly"isprovided'with' an end bore' 26 intowhich a reduced diameter roundcopper con tacting member-28 in the form of a rod is in serted with arelatively snugfit. The shoulder 30 thus formed-by the end of the shankportion 24 and the contacting member 28" is adapted'to receive andposition a steel sleeve 32 having a beveled end portion-34 suitablyshaped to abut smoothly against the-shoulder 30. The shank portion maybe preferably tin or nickel plated to prevent oxidation and therebyassure good heat conductive contact with the heater sleeve 10.

In practice, the contacting end 36 of the contacting member 28 isprotected against mushrooming by the sleeve 32, as is shown in Figure 3,the projecting end of the contacting member and sleeve being ofsubstantially the same length. As shown in Figure 3, the contacting endhas become from slight use somewhat concave, to afford a contacting areawith the head 38 of an explosive rivet 40. The steel sleeve 32terminates at or just short of the surface of the head 38 and therebyconfines the contacting tip from flowing or mushrooming as a result ofthe shock of detonation and the soft nature of the copper readilyaccomplished by removing the sleeve 32 which may not necessarily make avery tight contact with the contacting bar and thereafter removal of thecontacting bar from the shank to make room for the insertion of a newcontacting bar. It will be readily appreciated by those skilled in theart, that'the construction is such as to afford a tight connectionbetween the contacting bar and the shank portion for'the transfer ofheat therebetween. The steelsleeve being of relatively low conductingmaterial acts to some extent as a heat insulator, causing the contactingbar to conduct heat more readily to the tip without substantial heatloss. The slight air gap between the sleeve and the contacting bar addsto the insulating value of the sleeve.

While it is preferable to form the shank and contacting member ofrelatively pure copper because ofv the superior heat conductingcharacteristics of such material, other materials having similarproperties may be used if desired. The retaining shank may be made ofdrill steel or other material as maybe found suitable. The tip end ofthe contacting member may be flat to contact flat head rivets, or mayassume the concave shape shown for round head rivets.

, ,Though a single practical embodiment of the invention has beenillustrated and described, it is understood that the invention is notlimited to the particular iron shown or the particular shape of theparts illustrated. As various changes in construction and arrangement ofthe parts may be made without departing from the spirit of theinvention, as will be apparent to those skilled in the art,-referencewill be had to theappendedclaimsfora-definition of the limitsof theinvention.

.- -We.claim:--

. V 1. An explosive riv t=firing device comprising ashank portionadapted for exposure to a source of heat, a heating means sunrroundingsaid shank, a heat conducting rod extending axially from said shank andterminating in an end face having a plane contacting surface, said rodbeing of a material of high heat conductivity and relatively lowresistance to mushrooming from rivet explosion recoil in the regionadjacent said end 4 face, said rod at its rear end being received in anaxially directed socket in said shank and abutting the bottom of saidsocket, and a sleeve snugly surrounding said rod, and terminatingsubstantially flush with said end face, said sleeve being of arelatively hard material of relatively low heat conductivity and capableof confining said rod against radial expansion and preventingmushrooming under the recoil effect of an exploding rivet in contactwith the end face, the rear end of said sleeve abutting the front end ofsaid shank for securing said sleeve against axial movement along saidrod in a direction away from said end face.

2. A device according to claim 1, in which the rod is of copper, and thesleeve of steel.

3. An explosive rivet firing unit for insertion in arivet exploding toolhaving means for transmitting heat to said firing unit comprising a heatconducting rod terminatingin a single transverse continuous smooth endcontacting surface, said rod being of a material of high heatconductivity and relatively low resistance to mushrooming in the regionadjacent the end surface from rivet explosion recoil actingsubstantially normal to said end surface, and a sleeve snuglysurrounding said rod and terminating substantially flush with themarginal edge of said single end surface at all points thereof toconfine the rod, said sleeve being of a relatively high strength hardmaterial of relatively low heat conductivity and capable of confiningsaid rod against radial expansion and preventing mushrooming under therecoil effect of an exploding rivet head in contact with said endsurface, and rigid abutment means coacting with said rod and said sleevefor prevent-1 ing rearward, axial movement of said rod and sleeve andmaintaining the sleeve end substantially fiush with the forward endsurface of said rod.

VERNQN M. BUNTS. HENRY C. HOLBERT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 2,411,859 Harwood Dec. 3, 1946

